The invention relates to printing presses and in particular to a new and useful device for the drawing in of material webs in rotary presses by a driven draw-in element of finite length operating along guides which lie outside the cylinder area and which are equipped with branchings by which the draw-in path is pre-adjustable.
Such devices for the drawing in of material webs in rotary presses are already known. Thus, for example, German patent No. 20 21 246 shows a draw-in device in the form of a motor carriage which introduces a paper web into the rotary press along a cog rail guide on a desired guide track adjustable by means of switches.
A further draw-in device is shown in German patent No. 22 41 127. There the draw-in element (which is movable back and forth in guides along the draw-in path adjusted by means of switches, the drive elements being fast to the machine frame) has a finite length extension and is flexible.
These devices have the disadvantage that the guides for the respective draw-in element must be mounted fixed without a gap along each desired draw-in path, resulting in particular in the area of the printing units in a great accumulation of guides, which at least complicate the free access to the printing units.
Another disadvantage consists in that, especially in the multiple printing of a material web, the web is guided around adjustable register and/or regulating rolls. As the position of these rolls within an adjustment region may be any, the guiding of the draw-in element must make it possible that as the material web is being drawn in, these rolls are enveloped by it in any event, regardless of the position of the rolls. What this means is that the guide must go around the roll when the roll is in its extreme position, i.e. when the draw-in path, for example, between two printing units has the greatest possible length. But if the roll is not in the extreme position, as is normally the case, there occurs during the draw-in process of the material web a so-called bag formation, which is undesirable and disturbing.